diff --git a/stonesoup/models/transition/nonlinear.py b/stonesoup/models/transition/nonlinear.py
index 9b4feffd4..d9d49d599 100644
--- a/stonesoup/models/transition/nonlinear.py
+++ b/stonesoup/models/transition/nonlinear.py
@@ -3,7 +3,7 @@
 import numpy as np
 from scipy.linalg import block_diag
 
-from ...types.array import StateVector, StateVector
+from ...types.array import StateVector, StateVectors
 from .base import TransitionModel
 from ..base import GaussianModel, TimeVariantModel
 from ...base import Property